Graft preservation in haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide: single center experience

Abstract

Haploidentical stem cell transplantation (haplo-SCT) is often used as a treatment option in the absence of HLAmatched donor. Cryopreservation of the graft allows pre-preparation of the bone marrow, which has become especially important during the COVID-19 epidemic. As cryopreservation remains to be relatively less studied in the context of haplo-SCT, we conductеd a retrospective analysis of its feasibility in our patients. Medical records search identified 113 patients with various oncohematological diseases, who received haplo-SCT with (n=68) or without (n=64) graft cryopreservation between 2015 and 2020. Graft-versus-host disease (GvHD) prevention with post-transplant cyclophosphamide was used in all patients. Both cohorts of patients were comparable in terms of recipient age and gender, disease activity, graft source, and rates of major AB0 incompatibility. Age of donors was significantly higher in cryopreserved graft recipients (45 vs 37 years, p=0.017). Rates of acute and chronic GvHD, disease relapse, as well as PFS and OS did not significantly differ between the two studied cohorts. There was also no difference in terms of granulocyte and thrombocyte recovery. Although, in univariate analysis, cryopreservation significantly increased risk of graft rejection (34.3% vs 15.4%, p=0.02) and secondary graft failure (19.5% vs 4.4%, p=0.02), in multivariate analysis, there was only a trend towards increased risk of secondary graft failure with cryopreservation (p=0.096). As a summary, our data suggest that graft cryopreservation during haplo-SCT with post-transplant cyclophosphamide has no negative impact on key SCT endpoints.